Almost 12,000 tickets have sold for the must-win clash against the Cherry & Whites and Ospreys bosses are anticipating an electric atmosphere for a game crucial to their hopes of Heineken Cup final eight progression.
"We are confident that the crowd will exceed the 16,509 New Year's Eve attendance making it the highest of the season, and we're hopeful that we will achieve, or get very close to, our first sell-out of the season," said Ospreys Managing Director Roger Blyth.
"If we do, it will give everybody at the region a huge boost, and for the players to run out in front of more than 20,000 fans for such a huge match will be fantastic.
"Undoubtedly, a big crowd and the improved atmosphere that comes with it has a massive impact on the players and in such a crucial game, every little thing that can make a difference helps. The gap between success and failure can be very narrow indeed so we want our supporters to come from all corners of Ospreylia on Saturday to help roar us to victory."
According to Blyth, the crunch match on Saturday will be reminiscent of days of old when Welsh sides would regularly face English opposition throughout the season, although he says that the Heineken Cup has given the clash an exciting modern twist.
He added: "Back in the amateur days, before the pressures that leagues and professionalism brought with them, these Anglo-Welsh matches were a regular fixture in the schedules and they were always played out in front of bumper, passionate crowds.
"When the opposition only had a short trip across the Severn Bridge, such as Gloucester on Saturday, the atmosphere would always be fantastic. Large numbers would travel down the M4 looking to put the Welsh clubs in their place and I'm sure that it won't be any different this weekend.
"These days, such matches are much rarer, and unlike the Anglo-Welsh matches of old, these games have the added spice of silverware being up for grabs. I think it will be another fantastic occasion for Ospreys supporters, whether they are old enough to remember the amateur days or youngsters to whom the concept of regular Anglo-Welsh rugby is unheard of.
"Gloucester are set to have a large following presence judging by the number of tickets being posted out to supporters in their catchment area, which will help to add a bit of spice to the atmosphere and will ensure that our own supporters will have to do their bit to make themselves heard over the travelling support on the night."
Lyn Jones's men will be gunning for revenge against a side that handed them their only Heineken Cup defeat so far this season when they met at Kingsholm back in November.
Two early Sonny Parker tries put the Ospreys in the driving seat only for the Cherry & Whites to come roaring back to clinch a 26-18 success that handed them the initiative in Pool 2.
They sit proudly on top of the Guinness Premiership despite suffering only a second league defeat of the season on Friday night when they lost narrowly to local rivals, against second placed Bath.